I have a problem Im trying to figure out on what is going on. Basiccly car is only firing on 3 cylinders, the car has spark on all 4 cylinders, but on the injectors only 3 are firing and the one not firing is the third cylinder.

Car has 370cc Prelude Injectors with a resistor on a chipped p28 ECU.
1988 CRX w/ OBD0 to OBD1

I have changed ECUs, Changed Injectors around, Ran volt meter to the injector and it is not putting out any readings, while the others do, changed the wiring on the resistor. And also ran the wire straight from the ECU to the injector and still nothing. Only the blue wire.

I'm stuck to what the problem can be. If anyone can lead me to the right direction I would appreciate it. Thanks

 

Did you check your harness that plugs into the ecu to make sure none of pins are bent are missing?

 

yes I checked the wiring, like I said I went straight from ECU to injector and still no power

 

try changing the injector itself. youll be fine with a stock one just to test it out. maybe its just a dead injector

 

Doesn't the ecu supply voltage to the injector to open it? Isn't it constantly grounded? In that case you wont see voltage unless the injector is firing. And I don't think you can see it switching with a voltmeter cause the way most voltmeters sample and average the reading and then display the info.
You need a "noid light" to see if the injector is firing receiving the correct opening signals from the ecu.
Check all the injector wiring and verify at that one wire on each is grounded.

 

When car is idling all the other injecz
Tors give me signal, but the 3 cyl. I'm thinking the ground part of my injector is bad because when I give it straight power from the ecu to injector still nothing. I also know the injector is good because I changed it around with a working one and still nothing

 

If you suspect your ground is bad, then check it with a multimeter.

 

Have you pulled the rail and actually watched the injectors fire? Or is this just a guess..?

 

I checked with a voltmeter and the only one not giving me signal is from the cyl 3. Changed the injectors around and still nothing. Swapped out ecu's too. Only other idea is the ground on injector 3 wiring is bad

 

Did you VISUALLY watch the injectors fire? Yes or no.

If "no". Pull the rail, have a friend hold the injectors in place and point them outward towards the front of the car. If you do not hold them, you will blow them out of the fuel rail. Prime the car and try to spin it over watching each injector fire... Lets make sure its not firing for sure, instead of just guessing.

From there we can narrow it down to be either a bad injector, resistor or a wiring that isn't making a good contact.

 

Pulling the rail is a waste of time if it is not getting signal to open in the first place.

You said you changed the wiring on the resistor, did you try a new resistor?

 

How is it a waste of time, its 3 10mm screws or nuts. Takes five mins, he could be mis reading or something of that nature. Seeing the injector fire would help narrow down things.

If the injector is firing and its getting spark, its quite possible the valvelash might be too tight, and its not allowing for cumbustion to happen in the chamber.

He could be not reading a wire right.. something could be crossed, its a simple diag thing for most of us, but i would just pull the rail to be safe, but whatever. Good luck.

 

Check the wiring with a multimeter from the injector plug to the shock tower plug then from the shock tower plug to the ecu to find where the wire is bad. I had to rerun an injector wire on my friends car the other day from the injector plug to the shock tower.

 

did you ever fix it? what was the problem

 

I'm having the same problem same injector on a stock jdm itr with virgin never touched p73

 

Just to sort out some misinformation in this thread. The ECU is the ground source for the injectors. The power source goes through the resistor box to the injector.

Pulling the fuel rail to check injectors is not always necessary. Check for voltage at the injector, if there isn't any than there is no need to remove the fuel rail. You would have to trace the wires to find the open/short in the circuit. If this is happening with only one injector. The short could be anywhere from the resistor box to the ECU.

Make sure you have the injectors wired/grounded to the appropriate pins on the ECU for your specific year.